[ubuntu-cloud] Ubuntu cloud image '-root.tar.gz' content changes

Robert Collins robertc at robertcollins.net
Mon Oct 28 19:07:37 UTC 2013

On 29 October 2013 07:46, Scott Moser <smoser at ubuntu.com> wrote:
> Hi all,
> tldr;
>   As we look forward to the 14.04 deliverable of cloud images, we're wanting
>   to reduce legacy formats and streamline those that we have.
>   If you're a consumer of the '-root.tar.gz' file then read on.
>   The change suggested here will *only* affect the -root.tar.gz file.
> We make several formats of images available on cloud-images.ubuntu.com.
> The one relevant to this mail is the '-root.tar.gz'.  This is essentially
> a 'tar -cSpzf - /' of the contents of /.
> The changes we've just made to trusty are to remove the kernel and
> bootloader packages before creating the tarfile.  Essentially doing a
> 'apt-get --purge remove "linux-*" "grub-*"' before packaging.
> The reasoning for this is
> a.) the images will then be more similar to the ubuntu core tar files at
>     http://cdimage.ubuntu.com/ubuntu-core/releases/12.04/release/
> b.) the images are primarily used for lxc, where a kernel and bootloader
>     are not necessary or used.
> c.) there is a ~25M reduction in the size of the tarball, and a 100M+
>     reduction in the size of the extracted root.
> I'm interested in hearing feedback from anyone using these images that
> would be [negatively] affected by the proposed change.

Hi, we use those images (the root.tar.gz) ones for diskimage-builder
in OpenStack. We build both vm and baremetal images from them, and
currently assume that there is a kernel in them (but we do remove grub
from them early on). Overall I think this is probably a good idea, but
we'll need to fixup our code to be a bit more explicit about whether
the output is for a vm or physical machine.


Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud

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